This invention relates generally to pan and tilt mounting mechanisms used with equipment which must be frequently and accurately repositioned. More particularly, this invention relates to remote controlled pan and tilt mechanisms for use with cameras.
Remotely controlled video cameras are widely used today and their use and application is increasing. They are used for surveillance purposes in structures such as airports, stores, banks, warehouses, and a number of other locations too numerous to list. They are further used to collect and transmit data to human users from locations where humans are unable to observe first-hand. These areas include areas which are either hazardous to human health, such as toxic waste sites, or areas where humans are physically unable to enter, such as pipelines.
In order to maximize the visual data collected, a goal of these video systems is to provide the camera with as full a range of motion as possible. Consistent with this goal, these video cameras are usually mounted upon a pan and tilt head which is designed to rotate about a vertical axis (i.e. pan the camera) as well as about a horizontal axis (i.e. tilt the camera). This sort of mechanism provides the camera with a virtually limitless range of motion thereby maximizing the amount of visual data capable of being collected by the camera.
Present systems generally incorporate a motor and gearing system to achieve this motion. Specifically, these systems utilize a gearing system to provide the panning motion and a second gearing system to provide the tilting motion. Each of these gearing systems is powered by a single motor.
While these types of systems provide the range of motion desired, they do have their inherent disadvantages.
First of all, the designs are complex, employing a number of moving components. This makes repair and maintenance difficult and costly at times.
Further, where a high degree of accuracy is required, these systems may not be adequate. Specifically, normal machining tolerances permit some free play or "backlash" between the gear components. This results in the camera focusing on a point other than what it is intended to. This error may not be critical when the camera is focusing on a relatively near object, but when the point of focus is farther away, the error is greater.
While some designs have attempted to solve this inaccuracy problem inherent in gear-driven pan and tilt mechanisms, none have solved the problem utilizing a cable-driven pan and tilt mechanism. Further, the proposed solutions add to the complexity of the mechanism.
Considering these drawbacks and the proposed solutions, it is clear that a simple, low-maintenance and low-cost pan and tilt mechanism is needed that will provide the range of motion desired while still providing the accuracy required. The following invention accomplishes these goals.